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Ubuntu – How to bind a socket to a multicast UDP port on Windows-10 with python?

This is a python-related programming question that maybe cannot be answered at all. Maybe there is no solution.

But here is the setup: I am using Windows-10 on a hp laptop and a device in a local network sends out UDP packages for destination 239.0.0.4 and port 45004 (As can be confirmed via wireshark). That device is connected to a USB Ethernet connector named Ethernet with a static IP address 192.168.200.5 and subnetmask 255.255.255.0.

enter image description here

I am trying the following python (3.10.11) code to create a socket in order to read the packages from that device (the exact same python code works without any issues on Ubuntu on the same laptop and the same device):

import socket

mcast_grp = "239.0.0.3"
port = 45004
adaptor = "192.168.200.5"
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind((mcast_grp, port))  # FAILING LINE
mreq = struct.pack("4s4s", socket.inet_aton(mcast_grp), socket.inet_aton(adaptor))
sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

But that python code fails on the indicated line with the error

    sock.bind((mcast_grp, port))
OSError: [WinError 10049] The requested address is not valid in its context

Is there ANY way to rewrite this python code so it also works on windows?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    To capture the data from an ethernet device using python on Windows-10 it is possible to use the third-party module pyshark. That allows to capture and select the requested packets from the device.

    Here is an example code how to do that:

    import pyshark
    
def capture_ethernet_traffic(interface, destination_ip):
    capture = pyshark.LiveCapture(interface=interface)
    for packet in capture.sniff_continuously():
        # Select UDP packets directed to a certain IP address
        if "IP" in packet "UDP" in packet and packet.ip.dst == destination_ip:                   
            # Extract the data as bytes
            captured_data = bytearray.fromhex(packet.data.data)
            print(captured_data)

            # process that data as required
            ...

interface = "Ethernet 7"  # Replace with your interface name
destination_ip = "239.0.0.3"
capture_ethernet_traffic(interface, destination_ip)

    Works like a charm...


  2. 0

    You can’t bind the socket to a multicast group IP, only to a local interface IP. So bind to the IP of a local adapter that you want to receive packets on, and then subscribe to the multicast group to indicate that you want to receive packets from it.

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